Estimation of Magnetic Fields Generated by Overhead Transmission Lines, in Locations of Continuous Exposure

The magnetic fields generated by power transmission/distribution equipments along with the possible chronic effects associated with them have been objects of study and concern over last decades. This work comes in this context of magnetic field possible chronic effects. The objective of this work is then, for some overhead distribution lines, to create three-dimensional models of the lines and to extrapolate the magnetic fields for close location with continuous exposure. For this makes use of specialized appropriated software, the EFC-400 from Narda company, and magnetic field measurements made in the vicinity of the overhead lines. The overhead lines studied attempt to cover every kind of overhead distribution lines existents in Portugal. The overhead lines are then three simple ones and two double ones. The simple ones are of 10, 30 and 60kV and the double ones are of 30 and 60kV.The obtained results show that, for the daily media charge, the only situation where the magnetic fields exceed the value of 1μT (reference limit value adopted by Switzerland) is in the residential buildings just near the 60kV double line.